UV Light and pregnancy
It is known that having extra folate before getting pregnant and during the early part of pregnancy provides some protection for the developing baby from abnormal development of the brain and spinal cord (protection from developing spina bifida and other neural tube defects). It has also been shown that exposure to UV light lowers the level of folate in blood in tests in the laboratory. Researchers are starting to look at whether too much exposure to UV light around the beginning of pregnancy can lower folate levels enough to make the baby more likely to develop abnormally.

It is especially important to avoid excessive temperatures during the first trimester (I guess it eliminates saunas and hot baths as well). Later in pregnancy excessive heat can trigger premature labour (about that fact there is no doubt).

Additionally, pregnancy makes your skin more sensitive to the sun, so it can increase your chance of rashes and chloasma (dark patches on the face that often accompany pregnancy – but I guess they won’t worry you that much if you give birth to handicapped child).

Tanning in Pregnancy in Sun beds:
Apart from increased skin cancer danger to Mum, sun beds have the same effect as the sun – they increase body temperature and break down folate, except they can do it on much deeper level, so carry even higher risk. In solarium beds concentrated doses of UV radiation can be up to five times the strength of the midday summer sun. So theoretically you increase your chances of having a baby with damage to nerves and spinal cord by 5 times. Scary!

So, the bad news is: you should NEVER consider sun, or solarium tanning in pregnancy. The complications, although don’t happen every time, are so severe that they could affect your and your baby’s whole life.